This research program aims to understand stimulus discrimination, generalization, and attention, all of which are fundamental to adaptive behavior. These processes, together with their disorders and physiological substrates, are currently under intense study with both humans and animals. In the present experiments pigeon subjects are used for their excellent vision, probable simplicity of underlying processes, and extensive background research available. The birds work for food reward in visual search and discrimination tasks. In some experiments the subjects are supplied with advance information about upcoming search or detection targets; in others, difficult discriminations are tested, together with variations in the probability of reward. Such operations explore the nature of attention, pattern recognition, incentive, and memory retrieval processes. The work stresses the collection of quantitative data suitable for mathematical modeling; an exemplar model of discrimination and memory is used to predict key results.